Tire air pressure

[Dinky]

People like you are almost impossible to help. You are so focused on proving how smart you are and how dumb everyone else is that you don't even bother to check out the information we take a lot of work to provide. Just one example of 35 inch from the same site. They go way up in size from there. If you can't use a computer or simple search function, don't blame it on me.

35x12.50R18 Tire Pressure

Discover the load limits at various inflation pressures for 35x12.50R18 tires to ensure optimal tire performance and a safe drive.

tirepressure.com

Lol I was kinda joking there bub. I did look at your link and but the image didn't show it . I am aware of finding it on a search I am pretty savvy finding information on how to fix things. I am the type of person that I have to research it and do it myself and can not learn from a book lol.

 

[Daniel Ortiz]

So I found this article that largely describes what I was talking about in my last post. I didn't mean tire pressures are ONLY determined by handling. I think loading is the primary concern, but handling is probably second, and wear and comfort probably third.

Anyway, here's the bit that describes what I was talking about:

**********

The Ford-Firestone Factor​

"For passenger cars, SUVs and light trucks, the load curve number launches a series of negotiations. The engineers responsible for the vehicle’s handling are likely to lobby for additional inflation pressure to improve handling. Similarly, lower rolling resistance results in better fuel economy and leads to demands for higher inflations. Cars likely to see high-speed bring with them engineers insisting on more air pressure. On the other hand, ride considerations are an important consideration and that calls for lower inflation pressures.

"Today, the results of these nego-tiations are inflation pressures typically in the 32 psi to 35 psi range. If the champions of improved ride had their way, the 26 psi to 28 psi range that was common a few years ago would be more common. The safety factor of the higher inflation pressure seems to be carrying the day with automakers. After all, no one wants a repeat of the fiasco of when Ford set the recommended pressures on first generation Explorers at 26 psi.

"In that situation, recommended inflation pressures too low to provide an adequate safety factor were frequently combined with poor maintenance, overloading and high ambient temperatures to produce a series of often-deadly accidents (250 deaths and 3,000 serious injuries were attributed to the problem)."

**********

Funny enough, they also point out that the debate about tire pressures is anywhere near settled:

"Look at some of the online forums and you will see that the arguments about relying on the placard or the tire sidewall can be animated."

Like I said, just something to think about. Read the whole article, it's pretty interesting. Of course, the only way we would ever be able to settle our tire pressure differences is to go track down and capture a full grown suspension design wizzard, and grill him till he spilled his secrets. But good luck finding one and making them talk.

 

[Shawn Burns]

I love this forum. These are some thoughtful responses and quality arguments. In the end, I think I'll stick with what I've been doing (door placcard + 5 psi for towing). The ride quality isn't the greatest, but that hardly matters to me. The wear is good (I live 3 miles from work and I put less than 10k miles/year on the truck) and the cornering response is as good as a pickup with A/T tires should be.

 

[Dinky]

So I found this article that largely describes what I was talking about in my last post. I didn't mean tire pressures are ONLY determined by handling. I think loading is the primary concern, but handling is probably second, and wear and comfort probably third.

Anyway, here's the bit that describes what I was talking about:

**********

The Ford-Firestone Factor​

"For passenger cars, SUVs and light trucks, the load curve number launches a series of negotiations. The engineers responsible for the vehicle’s handling are likely to lobby for additional inflation pressure to improve handling. Similarly, lower rolling resistance results in better fuel economy and leads to demands for higher inflations. Cars likely to see high-speed bring with them engineers insisting on more air pressure. On the other hand, ride considerations are an important consideration and that calls for lower inflation pressures.

"Today, the results of these nego-tiations are inflation pressures typically in the 32 psi to 35 psi range. If the champions of improved ride had their way, the 26 psi to 28 psi range that was common a few years ago would be more common. The safety factor of the higher inflation pressure seems to be carrying the day with automakers. After all, no one wants a repeat of the fiasco of when Ford set the recommended pressures on first generation Explorers at 26 psi.

"In that situation, recommended inflation pressures too low to provide an adequate safety factor were frequently combined with poor maintenance, overloading and high ambient temperatures to produce a series of often-deadly accidents (250 deaths and 3,000 serious injuries were attributed to the problem)."

**********

Lol firestone tires in fact were selling faulty tires plain and simple. Most of those cases were on Ford exploders which their suspension design made them tip over at every corner. Any tire under inflated during hot temp will blow out eventually and does need to be take in to consideration. As we stated above you need to adjust pressures because of weight and time of year. Running multiple caulk test for each event would give you the info you need. Running @Dean2 chart with weight will also work as it's cold tire pressure not hot. This has engineering specs behind it to allow the tire to heat up and still run safely. We have stated each tire and load will run differently. The door stick on your truck is only good for the wheel/tire size that came on your truck. Switching wheel and tire size will make it irrelevant.

 

[JessJoe]

My 2 cents..get it weighed then you will have information as to how to proceed

 

[Big3MG]

The tires that come standard on any Rebel are light truck (LT) rated tires requiring the higher pressures because the LT tire is almost twice as heavy, more durable, thicker rubber, etc. if you replaced with non LT rated tires then you need to lower the pressures to about 36 psi (the specified psi for other RAM 1500 trucks with non LT tires). Do not run the higher pressures on non LT tires. Unsafe. But…running the required lower pressures will trigger the TPMS low pressure alert. I have a 2020 Rebel and I have a set of wheels with non LT Goodyears that I keep at 36 psi for long road trips. I had to re-set the TPMS pressure threshold lower using AlphaOBD and a security gateway bypass on an android tablet.

 

[Big3MG]

If you are using an LT tire (which an E load range is) then use the pressures in the door decal. The higher pressures are needed for these heavy duty tires.

 

[DonF]

A quick and dirty way to set tire pressures is to feel the sidewall. You want them warm, that means the tire is working. What you don't want is for them to be hot; and by hot I mean that you think it will burn your hand if you leave it on the side wall.

I've used this method for years and have had very good success with it. I ran 50 psi front and 45 psi rear in my '98 2500 *empty*. Tires wore evenly. I'm still trying to find the right pressures for my '16 3500 SRT but at 70 psi front and 65 psi rear *empty* the sidewalls are cold or barely warm.

My Dad owned a trailer company and we built tag trailers running the 14.5 doughnut wheels. We had to use a 12 ply tire to carry the weight and if you didn't run 100 psi in them, they would fail due to the sidewall flexing excessively.

 

[lpennock]

The door placard on trucks has the pressure required for a fully loaded truck. If you pull the Tire load charts for the tire you will find the pressure specified for the tire exactly matches the GAWR/2 loading of the tire.

TRA in 2013 lobbied the NHTSA to require the placard and the TPMS to be set to that pressure. (TPMS actually is a % under that pressure for the alert.) At the time RAM and GM both showed that the max load pressure actually increased the stopping distance of an unloaded truck. They lost their argument because the chance of a tire failure due to overloading an underinflated tire was considered a higher safety risk than the slightly increased stopping distance.

Bottom line is the tire pressure can be adjusted downward for the actual truck load and will improve both ride and stopping distances. The improvement in stopping distance is more pronounced on the 2500/3500 as there is 40psi or more difference rear between unload and loaded pressures.

The chalk test is an approximation of what the load tables tell. The correct way to set tire pressure is take the truck to a CAT scale and have it weighted then pull the TRA load table for the Tire and set the pressure to the TRA data plus about 5psi for temperature changes and so you don't have to check pressures as often.

 

[4X4BOSS]

I have a 2019 PW...swapped out for 35/12.5/17 Nitto Ridge Grapplers on OEM rims...truck says 60 up front and 65 out back...lol
I run 40 up front and 35 in the back...wish I could get rid of the "low tire" light......grrrrrrr

 

[Hydrasport23]

The tag addressing the tire pressure on your vehicle is specific to your vehicle, hence the "vin#" on that tag. The weight of the vehicle is one of the most important reasons for the recommended tire pressures on that tag. The air in the tire is how the tire maintain it's shape. Studies have proven that a 20% reduction in the recommended tire pressure can cause severe tire deformation when it encounters water on the roadway at highway speeds. In other words, one of the leading causes of hydroplaning is low tire pressure.

 

[lpennock]

I have a 2019 PW...swapped out for 35/12.5/17 Nitto Ridge Grapplers on OEM rims...truck says 60 up front and 65 out back...lol
I run 40 up front and 35 in the back...wish I could get rid of the "low tire" light......grrrrrrr

You can reprogram the pressures using AlfaOBD. For your 2019 you will also need an security bypass cable.

 

[Dean2]

The tag addressing the tire pressure on your vehicle is specific to your vehicle, hence the "vin#" on that tag. The weight of the vehicle is one of the most important reasons for the recommended tire pressures on that tag. The air in the tire is how the tire maintain it's shape. Studies have proven that a 20% reduction in the recommended tire pressure can cause severe tire deformation when it encounters water on the roadway at highway speeds. In other words, one of the leading causes of hydroplaning is low tire pressure.

That study was done on passenger vehicles who's loaded and unloaded weights are fairly close. It was also done with non-LT tires. It does not apply to HD pickups that can have a 3000 pound or 40% variance in vehicle weight, from empty to loaded.

 

[Bandit1859]

I have a 16 Rebel. The door sticker recommends 55 front and 45 rear for the air pressures. The truck came stock with Toyo Open Country A/T. I now have Falken Wild Peak's on there with an 80 lb. max. Should I stick with what the door label says or increase them closer to the max? I've been running them at 60f and 50r when I town, just as I did with the Toyo's. The ride is improved since I switched to the Toyo's. Thanks in advance.

Follow OEM

 

[SpaceRanger1]

I have 216K on my 2017 Rebel.. First set of Toyo A/T 2's 84k on them. The second set A/T 2's 78K. Now I'm on Toyo A/T 3's 60k+ so far.. I run 60 psi hot, a tad stiff on a rough roads but with the Air Ride she's smooth.. I have 321's I get with 89 18-19 mpg. Any less in tire pressure it falls on it's face!!

 

[nlambert182]

Don't forget (I haven't seen this mentioned yet) that your rims have a safe working pressure as well. Make sure that whatever PSI you choose is within spec of the rim. Typically there is a stamping somewhere on the back of the rim that indicates the max tire pressure.

 

[lpennock]

Don't forget (I haven't seen this mentioned yet) that your rims have a safe working pressure as well. Make sure that whatever PSI you choose is within spec of the rim. Typically there is a stamping somewhere on the back of the rim that indicates the max tire pressure.

They also have a safe load rating. I ran into this on a SRW 3500 when going to 4K rated LT tires. Most of the rims for the 3500 at the time were rated at 3625lb and some were much less than that.

 

[nlambert182]

They also have a safe load rating. I ran into this on a SRW 3500 when going to 4K rated LT tires. Most of the rims for the 3500 at the time were rated at 3625lb and some were much less than that.

Yep. that's why I mention it. My 3500 had a similar situation with towing my fifth wheel. I ran into it again when I went to install a higher load rating tire of my fifth wheels rims.